A conventional sensor apparatus of this kind is described with reference to a drawing. FIG. 3 is an electric circuit diagram showing the conventional sensor apparatus.
As shown in FIG. 3, the sensor apparatus includes: first and second drive circuit sections 1A, 1B for outputting drive signals that drive detection device 2; and first and second detection circuit sections 3A, 3B for fetching response signals from detection device 2. The sensor apparatus further includes: first and second processing circuit sections 4A, 4B for fetching sensor signals from response signals from first and second detection circuit sections 3A, 3B; and output terminals 5A, 5B for outputting sense signals from first and second processing circuits 4A, 4B.
At least one of first and second drive circuit sections 1A, 1B, detection device 2, first and second detection circuit sections 3A, 3B, and first and second processing circuit sections 4A, 4B is set as an object of failure diagnosis and referred to as a failure diagnosis object section. Failure diagnosis circuit 6 electrically connected to the failure diagnosis object section performs failure detection on the failure diagnosis object section, and outputs a failure detection signal from output terminal 8 provided in failure diagnosis circuit 6.
It is to be noted that as related art document information concerning this application, for example, Unexamined Japanese Patent Publication No. 2004-301512 (Patent Document 1) is known. Such a conventional sensor apparatus has had a problem of low reliability under abnormality occurrence condition.
Specifically, in the above conventional configuration, there are cases where a sense signal is outputted from each of output terminals 5A, 5B before a failure detection signal is outputted from output terminal 8 due to a difference in passage channel of those signals. Even though a failure of the failure diagnosis object section has practically already been detected by failure diagnosis circuit 6, a sense signal under abnormal condition is transmitted to a controlled object such as an automobile. There has been a possibility of using a sense signal under abnormal condition for control of an automobile or the like, resulting in deterioration in reliability.